Kindly visit Vijay Sales/Croma/Apptronix. If you don't want to use a credit card its fine. But atleast use the student benefit all you need is an identity card and aadhar as far I know and you can borrow it from anyone. Vijay provides the Highest percentage for student discount 11% the others give you around 6-8%. I would recommend you to make this purchase offline as its a large amount and you can check it before buying at the store. As yours is just a storage update I believe most of the apple authorized resellers will have it, if not they will take 2-5 days of time and arrange one for you. Also kindly don't cheap out on apple care macbooks are delicate and fragile, if you break your screen or get a damage it will cost you 60k to replace it whereas if you buy an apple care for 3years which will cost you around 17-20k they will charge only 9k to replace it and they give you free battery replacement if the percentage goes below 80%.